The Great Salt Lake is the second saltiest body of water on Earth. The lake is over 72 miles wide, yet it is only about 10 to 28 feet deep.
In the past, hundreds of years ago, nearly a quarter of Utah was covered by Lake Bonneville. This was a fresh water lake. The lake was 900 feet deep at the site of Salt Lake City. The lake was so heavy that it depressed the Earth's crust so much that the shoreline can still be seen today.
The Great Salt Lake's salinity varies from between 15 and 25 percent. This is roughly six times greater then the salinity of the ocean.
The lake became so salty because of the many streams and rivers that flow into it. These deposit salt, and since there is no outlet from the lake, the salt remains.